Simultaneous determination for 5 human urinary metabolites of UR-144 and XLR-11 by LC-MS/MS

This study aims to explore how the abused synthetic cannabinoids in human urine can be determined qualitatively and quantitatively by using the LC-MS/MS method. As a method validation based on the current FDA guideline, we tested 55 human urine samples (5 from drug-free volunteers and 50 from drug abusers) and evaluated the presence of parent drugs (UR144 and XLR11) and their five metabolites (XLR-11-N-4-Hydroxypentyl, XLR-11-6-Hydroxyindole, UR-144-N-4-Hydroxypentyl, UR-144-N-5-hydroxypentyl, and UR-144-N-pentanoic). The experimental data showed that the values of low limit of detection (LOD) for these analytes ranged from 0.05 to 0.15 ng/mL. Their low limit of quantitation (LLOQ) value was 1.0 ng/mL. The values of linear coefficients of determination (R2) for these analytes ranged from 0.9914 to 0.9988. Among these 50 urine testing samples of drug abusers, the parent XLR-11 and UR-144 analytes were detected only in 4 samples (with a concentration of 2.14 − 4.5 ng/mL) and 3 samples (with a concentration of 3.2 − 5.4 ng/mL), respectively. At the same time, the XLR-11-N-4-Hydroxypentyl (with a concentration of 4.5 − 57.2 ng/mL) and XLR-11-6-Hydroxyindole (with a concentration of 4.8 − 51.7 ng/mL) metabolites were detected in 24 and 11 samples, respectively. In addition, the UR-144-N-4-Hydroxypentyl (with a concentration of 3.5 − 87.24 ng/mL), UR-144-N-5-hydroxypentyl (with a concentration of 14.5-83.9 ng/mL), and UR-144-N-pentanoic (with a concentration of 2.5 − 104.4 ng/mL) metabolites were found in 26, 29, and 38 samples, respectively.